A self-propelled vehicle is structured so as to convey a passenger and cargo, for example, in a self-propelled vehicle such as a dump truck, which has an engine mounted thereon and which conveys a loaded material. There is one which automatically detects an engine condition and makes a maintenance plan, a renewal plan, and the like. As the engine condition to be detected, there are the engine output and the specific fuel consumption. Then, conventionally, almost all of them are planned on the basis of the engine condition at a time of detection.
Further, in each of Japanese Unexamined Patent Publication Nos. 47-26053, 58-84394, 58-84397, 58-148912, 59-98935, and 59-119494, there is described a structure for storing detected data in a memory mounted on the vehicle and for moving the data to a magnetic card when desired, for inputting the detected data to a microcomputer and the like within a building for calculations.
Still further, in Japanese Unexamined PCT Publication No. 5-500559, there is described a structure of calculating with detected data, by a microcomputer mounted on a vehicle, so as to diagnose a trouble in the engine; and in Japanese Unexamined Patent Publication No. 4-279824, there is described a structure for displaying a specific fuel consumption by a graph on a display apparatus mounted on the vehicle.
However, in the conventional apparatus of the self propelled vehicle mentioned above, there are the following problems.
(1) In the method on the basis of the engine condition at the time of detection, since the data is detected in a pinpoint manner, a trend in the engine condition cannot be determined. Accordingly, there is a problem in that serious trouble can occur before the planned maintenance period or the renewal period, or in that a maintenance or a renewal is performed in spite of good condition.
(2) In the techniques described in each of the publications, the details of the engine condition can not be sufficiently determined.
(3) In the self-propelled vehicle which mounts the engine thereon and conveys a loaded material, in addition to the engine condition being automatically detected and the maintenance plan, the renewal plan, and the like, being made on the basis thereof, it is important to make a maintenance plan, a renewal plan, and the like for the entire vehicle by considering the work load. However, the conventional diagnosis apparatus is insufficient in this regard.